Why does fullscreen mode change video stretch? How to avoid?

I notice that ﻿﻿﻿ConfigureVideoSize() sets ActiveMediaPlugin.Stretch to Stretch.Uniform when in fullscreen mode. Why does this happen? What is this behavior used for?

I do not see any way to disable this behavior without making a custom build of MMPPF, which I would like to avoid. Please add a possibility to disable this in the next version.

My scenario is: the "natural" video size info is not reliable, so I want to set the video stretch to Fill and manually control the size using a wrapper element around the ﻿MediaPresenterElement. This works fine in non-fullscreen mode, but is undone by the
stretch-reset logic in fullscreen mode.

Right now, I am doing a workaround by setting the Stretch back to Fill after fullscreen change, but this does appear to cause a 1-frame flicker where it is rendered with Uniform stretch. So this is not an optimal solution.